1. Field of the Invention
This invention relates to an image recording system including a solid state image transducer provided with a great number of photoelectric elements independent of each other, an image forming optics for forming an image of an object on the image transducer, and a recording medium on which the image signals for the object image obtained from said solid state image transducer are reproducibly accumulated.
2. Description of the Prior Art
It is already known in the television especially color television art to employ the so-called charge transfer device such as CCD and BBD as the image sensor, for example, in U.S. Pat. No. 3,982,274. It is further known to provide a method and apparatus for recording and reproducing still pictures by processing the output of said device in such a manner that the image signals, after having once been stored, are read out at a relatively slow velocity and then converted to video signals which are to be recorded on a magnetic recording medium such as a magnetic disc, as, for example, disclosed in U.S. Pat. No. 4,057,830.
These prior art systems, however, places a limit of the discussion for their features on the mere function of recording the image signals on the magnetic recording medium, and disclose nothing about the exposure level control in producing the image signals. For this reason, the prior art system tends to record some of the image signal in an over-exposed state, and some in an under-exposed state, so that the reproduced image of optimum tone-reproduction quality cannot be obtained.
As the solid state image transducer, it is desirable to use a charge transfer type device such as CCD and BBD, or X-Y address type device, or charge injection type device (CID). But, because these devices are fabricated in the form of integrated circuits on a silicon semi-conductor substrate of thin thickness, when the image-receiving surface of the solid state device is accidentally exposed to a very intense radiant energy particularly from the sun through the image forming optical system, there is a high possibility of occurrence of suddenly heating the exposed surface of the device in a portion thereof to so high a temperature that the solid state device is burned to damage. Another disadvantage of the prior art system is that the recorded image is monitored by making use of an optical finder similar to that in the conventional photographic camera.
The prominent characteristic feature of such electronic image recording system over the photographic camera using the conventional photosensitive material of the silver halide type is, however, the enjoyment of the possibility of instant reproduction of the recorded image signals by means, for example, of the television set.